MOLECULAR CHARACTERIZATION OF SOME ENIGMATIC LOWER DEVONIAN FOSSILS

The coalified remains of three extinct nonvascular Lower Devonian plan ts (Prototaxites Dawson, Pachytheca Hooker, and Parka Fleming) have be en analysed using flash pyrolysis-gas chromatography-mass spectrometry , FTIR, and C-13 solid-state NMR. The affinities of these fossils are unknown and their habitats remain conjectural. Host rack lithology and grain size correlate with the state of morphological and chemical pre servation of Prototaxites. The Bash pyrolysates of well-preserved Prot otaxites and Pachytheca were dominated by aromatic hydrocarbons and al kylphenols. Given their resistance to compression when compared with a ssociated lignified vascular plant fossils, it is possible that Protot axites and Pachytheca contained an extinct polyphenolic structural bio macromolecule that was a failed experiment during terrestrialization. Precise affinities for the enigmatic fossils Prototaxites, Pachytheca, and Parka are still to be confirmed, although Prototaxites and Pachyt heca are chemically distinct from Parka. Copyright (C) 1998 Elsevier S cience Ltd.